Oil Separator
Oil Separator
(OP)
We are going to replace 2 reciprocating compressors on a chiller unit. These compressors share a common circuit. Outdoor air cooled condensers, chiller barrels inside below condensers. One contractor wants to install suction accumulators and oil separators. Two other contractors would not bid on either of those items. I'm leaning towards installing accumulators (~8% costlier) and forgetting about separators (~25% costlier). Any suggestions?
Thanks, Gatt
Thanks, Gatt





RE: Oil Separator
Liquid Accumulators
Liquid flood-back is liquid refrigerant returning to the compressor’s crankcase during the running cycle. Refrigerant migration is refrigerant liquid or vapor returning to the compressor during the off cycle. Migration usually happens because of a pressure difference. The compressor can be located in a cold ambient causing a lower pressure, or the oil can be attracting the refrigerant because of its lower vapor pressure. In either case, the refrigerant will migrate to the compressor because of its lower pressure. The causes of compressor floodback include:
· Wrong TXV setting (low or no compressor superheat);
· Overcharge;
· Low load on evaporator;
· End of cycle (lowest load);
· Dirty or blocked evaporator coil;
· Expansion bulb loose on evaporator outlet;
· Oversized expansion valve;
Suction line accumulators are designed as compressor protection devices when flooding and migration do occur. So depending on your particular application you need to look at the above and determine whether these are possible conditions you will have.